The addresses of these symbols indicate the end of various program
segments:
etext This is the first address past the end of the text segment
(the program code).
edata This is the first address past the end of the initialized data
segment.
end This is the first address past the end of the uninitialized
data segment (also known as the BSS segment).

The program must explicitly declare these symbols; they are not
defined in any header file.
On some systems the names of these symbols are preceded by
underscores, thus: _etext, _edata, and _end. These symbols are also
defined for programs compiled on Linux.
At the start of program execution, the program break will be
somewhere near &end (perhaps at the start of the following page).
However, the break will change as memory is allocated via brk(2) or
malloc(3). Use sbrk(2) with an argument of zero to find the current
value of the program break.

This page is part of release 4.08 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2008-07-17 END(3)